Fluid handling devices



p 1965 R. s. WADDINGTON ETAL 3,207,388

FLUID HANDLING DEVICES 2 Sheets-Sheet 1 Filed July 25, 1963 p 1965 R. s. WADDINGTON ETAL 3,207,388

FLUID HANDLING DEVICES 2 Sheets-Sheet 2 Filed July 25, 1963 United States Patent 3,207,388 FLUID HANDLING DEVICES Rogor Strange Waddington, Putney, London, and Bruce Duval, Woldingham, Surrey, England, assignors to Waddington & Duval (Holdings) Limited, a company of England Filed July 25, 1963, Ser. No. 297,493 Claims priority, application Great Britain, July 25, 1962, 28,615/62 3 Claims. (Cl. 222-484) The present invention relates to devices for handling liquids and especially to air reflux devices which when arranged through the wall of a closed container holding a liquid, being, for example, held in the filling aperture of a can, present a liquid entrance and an air exit to the liquid and enable the liquid to be delivered as required from an exit aperture positioned outside the container. Examples of such devices are described in our prior Patents Nos. 2,708,058 and 2,842,291.

The air reflux devices known hitherto have been arranged to keep the air stream separate from the liquid stream, at least until the air stream has reached the level at which it is to enter the liquid. Our said Patent No. 2,708,058 describes, for example, a device in which a completely partitioned air flow path is provided from an air entrance to an air exit positioned to communicate directly with the container. It also describes a device in which a partition allows air to ascend from an air entrance, out of contact with the liquid, until it reaches the level at which it is to be discharged, at which level the air passes through an air exit and then flows in contact with the liquid to enter the container through the upper part of the liquid entrance. In both devices the air entrance is located adjacent to the liquid outlet and positioned to be directed downwardly, this arrangement fulfilling an essential requirement that any liquid ejected from the air inlet by excess pressure in the container can be collected with the liquid from the liquid exit.

In accordance with the present invention there is provided a device for withdrawing a liquid from and simultaneously passing air to a container which comprises a tubular body having, leading between its exterior and its interior, a liquid entrance, an air exit which is small compared with the liquid entrance, and a liquid exit, the interior of said body providing a flow pathway for air to flow in one direction to the air exit and liquid to flow in the opposite direction to the liquid exit in streams which contact one another. The arrangement whereby the air is allowed to flow in contact with the liquid before reaching the air exit enables internal partitioning to be dispensed with and so enables a very simple construction to be adopted.

To be attractive in use, and even to be acceptable in use for dispensing liquid in small quantities, an air reflux device must deliver the liquid in a smooth stream, i.e. a stream free .or reasonably free from cyclic variations in the rate of flow. The device provided by the invention fulfills this requirement though not in such a versatile manner as do the devices described in our said prior specifications. The ability of the device to deliver the liquid in a smooth stream at a satisfactory rate depends upon the liquid itself. For example an embodiment of the device giving a satisfactorily smooth stream with oil at a convenient rate of delivery will give a violently cyclic flow with water, whereas an embodiment giving a smooth stream with water at a satisfactory rate will give only a very slow delivery of the oil.

It appears that the utility of an embodiment for a particular liquid depends upon the penetrability of the liquid by air flowing through the air .outlet. The penetrability depends upon the physical properties of the liquid, the

3,207,388 Patented Sept. 21, 1965 most important being the surface tension and the viscosity. In the important case of aqueous solutions of surface active detergents, the surface tension is negligible and the penetrability is principally governed by viscosity alone.

As will be appreciated, an arbitrarily chosen embodiment is primarily useful only with liquids having a suit able penetrability. Conversely the design parameters must be chosen appropriately when manufacturing an embodiment for use with a particular liquid.

In a preferred form of the device the liquid exit is the only aperture provided at the delivery end and is of such size that the air can enter thereby as the liquid is delivered. A separate aperture for the entrance of air, with or without a barrier to minimise access by liquid, may be provided in order to render the device more versatile but we find that this is normally unnecessary in practice.

The majority of liquids which we contemplate for use with the device have a lower penetrability than water at 15 C. and give a smooth flow with a device which will give a smooth flow with Water itself. Accordingly, taking water at 15 C. as a standard, the liquid exit is, in a convenient form of the device, at least large enough and the air exit is at least small enough to ensure that when the device is used with water at 15 C. as the liquid, a suflicient portion of the liquid exit remains clear of the water being delivered to permit air to flow through the liquid exit into the container smoothly at the rate required to replace the water.

An important class of liquids is the viscous aqueous solutions of surface active detergents. Their viscosity gives them a flow which is considered inconveniently slow when used with a device giving a smooth flow with water. Preferred devices for such detergents may conveniently be referred to an aqueous solution of a surface active detergent of viscosity centistokes as a standard instead .of Water at 15 C.; with them water itself should flow more than fast enough to fill the liquid outlet completely and interfere with the reflux passage of air.

The provision of a device for use with a particular liquid involves arranging the sizes of the air outlet, the liquid inlet and the liquid outlet to give a convenient rate of flow thereof. The maximum obtainable rate of smooth flow is determined by the cross section of the tubular body. It also depends upon the distance through which the liquid must flow from the liquid inlet to the liquid outlet. For a distance of up to twice the internal width of the tubular body, which usually represents the limit of convenience, the maximum rate approaches the rate of flow which would be obtainable through the liquid inlet under a head of the liquid corresponding with the internal height of the body; accordingly, in order to ensure a smooth flow, the air inlet should be made smaller than would be required to give this maximum with the liquids intended.

As with other air reflux devices, an important application of the present device is its incorporation in an assembly which serves for sealing a container for transit as well as facilitating withdrawal of the liquid. For this purpose the device may have a gland by which it may be located in fluid tight operative relationship with a container and be movable, or have a part which is movable, relative to the gland between a liquid delivery position and a container sealing position. One simple arrangement is to provide a gland through which the device, as a Whole, is movable axially between an outer position, in which the liquid inlet and air outlet communicate with the interior of the container whilst the liquid outlet communicates with the atmosphere, and an inner position in which the interior of the device is sealed from the atmosphere.

Constructions in which the tubular body is formed of a pair of relatively movable parts formed to provide a flow control function may be employed. In one very convenient form of the device, the tubular body is provided in the form of an outer sleeve, in which are formed the air exit and the liquid inlet, and a liner reciproeable in the sleeve said liner being formed with the liquid outlet; air and liquid can flow through the body only when the liner is positioned with the liquid outlet clear of the sleeve. Advantageously the liner is formed with apertures positioned and dimensioned to vary the degree of opening of the liquid inlet and air outlet with the position of the liner, and the liquid outlet is positioned and dimensioned such that when the liner is moved outwardly, the liquid outlet begins to open before the liquid inlet and the air outlet so that the rate of delivery of liquid can be regulated whilst maintaining a smooth flow thereof. A further refinement is to arrange that the interior of the liner is open to the interior of the container through or beyond the wall of the sleeve when the liquid outlet is closed by the sleeve, thereby enabling the liquid to be withdrawn in a series of equal portions by reciprocation of the liner. The liner fills when pushed inwardly and can be emptied whilst isolated from the liquid in the container, by pulling it outwardly to such an extent that the liquid outlet is partly open but the air outlet and liquid inlet remain closed.

Providing the tubular body in the form of a sleeve and liner is convenient in practice when, as is preferred, a gland for the purpose hereinbefore described is formed as part of the sleeve itself. To this end, the sleeve may be formed of flexible synthetic resinous material and part thereof grooved externally or otherwise shaped to be self locating in fluid tight relationship with an aperture such as the filling aperture of a container.

The following description of preferred embodiments of the device, in which description reference is made to the accompanying drawings, is given in order to illustrate the invention.

In the drawings:

FIG. 1 is a cross section showing part of a neckless, sheet metal, container of liquid with a first embodiment applied thereto,

FIG. 2 is an elevation of a second embodiment in the form of a sleeve, part of which provides a gland for a neckless container N (a section of which is shown), and a liner,

FIG. 3 is a longitudinal cross section of the sleeve only taken along line III--III of FIG. 2,

FIG. 4 is a transverse cross section of the sleeve taken along line IVIV of FIG. 3, and

FIG. 5 is an elevation of the liner only as seen from the right of FIG. 2.

The embodiment shown in FIG. 1 consists of a tubular body 1 closed at both ends and provided with a handle 2 at the outer end. It is formed near the inner end with a large liquid inlet 3 and a small air outlet 4. Near the outer end is a liquid outlet 5. Abutments constituted by a flange 6 and a peg '7 provide limits for axial reciprocation of the body 1 through a gland 8 by which it is held in fluid tight relationship with the flanged aperture 9 of a neckless, sheet metal, container N As will be understood, the outlet 5 is out of communication with the atmosphere when the body is pushed fully inwardly so that flange 6 contacts the gland 8; in consequence the container is sealed. With the body in the position shown in FIG. 1, liquid can enter the body via liquid inlet 3 to be delivered as a stream at the outlet 5. Simultaneously air can flow into the body via outlet 5 to enter the container at air outlet 4 provided that the emergent stream of liquid leaves part of the liquid outlet clear. The behaviour of the device depends considerably upon the penetrability of the liquid to air passing through the air outlet 4. Given a low enough penetrability, the rate of flow of liquid remains low enough to permit a 4? continuous flow of air through the liquid outlet and a smooth stream of liquid is obtained. Other factors being constant, a smooth flow is obtained with a liquid chosen to suit the dimensions of the air outlet or conversely the dimensions of the air outlet are made to suit the liquid with which use is intended. A conveniently high fiow rate with a liquid of low penetrability usually requires an air outlet unsuitable for easily penetrable liquids; e.g. a device for use with an aqueous detergent of syrupy consistency, is found to be unsuitable for use with an aqueous detergent of water-like consistency.

The embodiment shown in FIGS. 2 to 5 is constituted by two injection mouldings, viz. a sleeve 11 and a liner 12, slidable therein, both formed of polythene of bottle blowing quality and chosen for its high environmental stress crack resistance and good flex crack resistance. It has a specific gravity of from 0.920 to 0.929, a melt flow index of from 0.51 to 1.0 and a stitfness modulus of 21,300 lbs/sq. in.

At diametrically opposed positions the sleeve is formed with two longitudinal internal keyways 13 and 14 of rectangular cross section within ribs 13a and 14a raised on the outer surface of the sleeve and having a wall thickness, outwardly of the keyways which is small compared with the wall thickness of the sleeve, being 28% thereof in a typical ease. Externally the liner is formed with a longitudinal key 131; slidable within keyway 13, and with a protuberance 14b slidable within keyway 14. By this arrangement, rotation of the liner within the sleeve is prevented. Moreover the ends and 14c of the key ways provide, in co-operation with the key 13b and protuberance 14b respectively an outer limit for the reciprocation of the sleeve within the liner. An intermediate limit for the reciprocation, which corresponds with a position for the delivery of a fixed quantity of liquid, as shown hereinafter, is provided by engagement of protuberance 14b with a protuberance 13d which projects inwardly from the base of keyway 13. Because of the shape of the protuberances, and the thinness of the wall outwardly of protuberance 13d, the intermediate limit is characterised by an increased resistance to movement of the liner which is readily obvious to the user and readily overcome when required.

The liquid inlet of the device is provided by two adja cent rectangular openings 15a and 15b formed in the wall of the sleeve. Together they may be regarded as a single large inlet divided by a longitudinal rib 150. The air outlet is a circular hole 16 diametrically opposite the rib 150. The liquid outlet is a rectangular opening 17 formed in the wall of the liner.

For closing the liquid inlet and the air outlet and opening them progessively, the liner is formed with a liquid control port (provided, as with the liquid inlet itself, by two adjacent rectangular openings 18a and 18b and a dividing rib 18c) and with an air control port. The latter consists of a longitudinal slot 19 rounded at its ends.

Both ends of the liner are closed by a circular wall. At the outer end of the liner the circular wall 20 is set inwardly to provide a recess 21 in which is located a central boss 22, formed on the Wall 20 and having at its outer end an integral ring 23. The flexibility of this ring enables it to be crumpled into the annular space surrounding the boss 22 within the recess 21.

Outwardly of the opening 17, the liner is made slightly larger in its external diameter than the remainder thereof, typically by about 3%. The interior of the sleeve is dimensioned so that the sleeve has an interference fit, e.g. of 0.004", with the enlarged diameter part 23 of the liner and a close sliding fit with the remainder thereof. In spite of the enlarged diameter of its part 23, the elasticity of the sleeve enables the liner to be inserted into position via the sleeves inner end 24. Once the liner has been inserted, engagement of the inner end 25 of part 23 with ridge 26, at which the inner diameter of the sleeve is decreased to the minimum value, provides a substantial resistance to withdrawal and therefore an inner limit to reciprocation of the liner within the sleeve.

Because the liner can be inserted through the inner end of the sleeve, the outer end of the sleeve may be provided with an integral transit seal. In the example shown in FIGS. 2 to 4, the seal is a domed disc 27 united with the sleeve by short radial spokes 28 of triangular cross section. When the disc 27 is pulled by tab 28 the spokes break at their junction with the sleeve proper leaving it substantially free from attached residues.

Near its outer end, the sleeve is formed with a circumferential shoulder 29 for limiting its penetration through the opening of a container such as the inwardly flanged opening 30' of the neckless container N shown in part in FIG. 2. On its underside the shoulder 29 defines one side of a circumferential groove 30, the opposite side of which is defined by a shoulder 31 from which the outer surface of the sleeve tapers at 5 to level 32, beyond which the outer diameter of the sleeve is constant. Within the groove 30, is a circumferential rib 32. The inner surface of the sleeve has a circumferential groove 33, substantially wider than the groove 30 and positioned such that the opposed faces of the shoulders 29 and 31 both lie on the axial length thereof. The inner edge of the groove 33 is the ridge 26.

Together, the sleeve and liner provide a closure and dispensing assembly for the container N. When the assembly is inserted into the opening 30, the sleeve passes therethrough until the flange of the opening 30 engages the groove 30. The inside of the flange has an interference fit with the rib 32 and, with sheet metal containers manufactured to ordinary commercial tolerances, the arrangement of the rib 32 and the groove 33 ensures an adequate fluid-tightness without unduly stiffening the movement of the liner within the sleeve.

To dispense liquid from the container, the disc 27 is pulled away giving access to the crumpled ring 23 and the container is turned on to its side 34. If the liner is now reciprocated between its fully inward position determined by the ridge 26 and the intermediate position determined by the protuberances 13d and 1412 the liquid is delivered from the liquid exit 17 in a series of measured portions each equal to the internal volume of the liner. Liquid enters the liner by control port 18a, 18b and air leaves by the slot 19 when parts of these apertures project inwardly beyond the end of the sleeve. The sleeve covers them before the exit 17 begins to clear the outer end of the sleeve so that direct communication from the container to the atmosphere is prevented.

If the liner is pulled out beyond the intermediate position, the exit 17, already partly opened in the intermediate position opens further and the air exit 16 and the liquid inlet 15a, 15b begin to open as the slot 19 and the control port 18a, 18b respectively begin to register with them. Assuming that the interior of the can is free from excess pressure requiring to be relieved a smooth stream of liquid, accompanied by a reflux flow of air, is rapidly established when the liquid inlet 15a, 15b is open to a small degree. The rate of flow increases as the liquid inlet is opened to its full extent. Full opening of the air outlet is completed at the same time as full opening of the liquid outlet. Subsequent outward movement of the liner completes the opening of the liquid inlet as the key 13b and the protuberance 14b engage the ends 13c and 14c of the keyways.

Provided that the liquid has a low enough penetrability to air entering it via the air exit 16, the flow continues in a smooth manner with the liner pulled outwardly to its fullest extent; otherwise smoothness of flow is lost when the air exit is fully open.

Final direction of the delivery of the liquid is obtained by a spout 37 formed on the shoulder 29.

Reciprocation of the liner involves moving the apertures therein across apertures in the sleeve. Both components being formed of flexible material, there would be a pronounced tendency in the absence of the ribs and for the edges of the ports to obstruct the motion. The ribs, which do not add materially to the mechanical rigidity of the sleeve or liner effectively minimise the said tendency.

As will be appreciated the suitability of the device for dispensing a given liquid depends upon the design parameters. In an important case, the device shown in FIGS. -2 to 5 was intended for use with an aqueous surface active detergent having a viscosity at 15 C. of 253 centistokes. The following dimensions were adopted:

Inches Inner diameter of liner inwardly of part 23 0.892 Axial length of openings 18a, 18b 0.500 Total width across liquid control ports 18a, 18b, 18c 0.850 Width of dividing rib 18c 0.100 Axial length of liquid outlet 17 0.490 Width of liquid outlet 17 0.714 Total axial length of slot 19 0.770 Width of slot 19 0.188 Diameter of air outlet 16 0.172 Axial length of liquid openings 15a, 15b 0.485 Total width across liquid inlets 15a, 15b, 15c 0.870 Width of dividing rib 15c 0.100 Inner diameter of sleeve 1.020

The foregoing dimensions are all mould makers dimensions and allow for shrinkage of the mouldings amounting to 2%. The width dimensions are chordal rather than circumferential.

Very satisfactory results were obtained with the aqueous detergent and dilution experiments showed that substantial decreases in viscosity were well tolerated. With detergent of water-like viscosity, a smooth stream could be obtained only at low rates of flow, careful adjustment of the position of the liner being required.

It is to be understood that the present invention is to be regarded as providing not only a device as herein described but also (a) a container when equipped therewith, said container containing a liquid which the device is adapted to deliver as a smooth stream with reflux of air and (b) the method of dispensing a liquid from a closed container which comprises withdrawing .the liquid therefrom via the device with reflux of air, the liquid being one which the device is adapted to deliver as a smooth stream. The method may for example be applied as part of a process in which the liquid is used for such purposes as cleansing articles such as dishes, clothing or furnishings, lubricating machinery, protecting metal articles from corrosion or fueling engines.

We claim:

1. A device for use with a liquid container having a liquid opening therein to seal said liquid opening and to enable liquid to be withdrawn from the container whilst simultaneously passing air thereto, which device comprises a gland adapted to engage the liquid opening in fluid-tight relationship therewith, a tubular body reciprocable in fluid-tight relationship through said gland, a seal closing the outer end of said body, an aperture serving as an air entrance and as a liquid exit formed in the wall of said body near the outer end thereof, said aperture being exposed when said body is pulled outwardly through said gland, and concealed when said body is pushed inwardly through said gland, a liquid inlet to said body on the same side thereof as said aperture and an air outlet from said body on the opposite side thereof from said aperture, said liquid inlet and said air outlet being positioned to communicate with the interior of the container when said body is pulled outwardly through said gland, said aperture being at least large enough and said air outlet at least small enough to ensure that, when the device is used at 15 C. with a liquid having a penetrability by air flowing through the air outlet which is substantially less than the penetrability of a surface active detergent of'viscosity 150 centistokes at 15 C., a portion of the aperture remains clear of the liquid being delivered, which portion is sufficiently large to permit air to flow smoothly through the aperture counter-currently with the liquid and thence through the body, counter-currently with the liquid, and the air outlet at a rate sufficient to replace the liquid but insufiiciently large to permit such flow of air when the device is used at 15 C. with water.

2. A device for use with a liquid container having a liquid opening therein to seal said liquid opening and to enable liquid to be withdrawn from the container whilst simultaneously passing air thereto, which device comprises a gland adapted to engage the liquid opening in fluid-tight relationship therewith, a sleeve-like extension on said gland positioned to project from the opening into the container, an air outlet and a liquid inlet formed through said extension on diametrically opposite sides thereof, a tubular body closed at both of its ends reciprocable in fluid-tight relationship through said gland, an aperture serving as an air entrance and as a liquid exit formed in the wall of said body near the outer end thereof, said aperture being exposed progressively when said body is pulled outwardly through said gland and concealed when said body is pushed inwardly through said gland, an air control port formed in the wall of said body which port is positioned and dimensioned to lie out of register with the air outlet when the body is pushed inwardly through said gland and whilst the body is being pulled outwardly through said gland until said aperture is partially exposed and to register with the air outlet, thereby uncovering the air outlet from within, whilst the body is pulled further outwardly to complete the exposure of said aperture, and a liquid control port formed in the wall of said body and arranged to be open to the interior of the container at least when the air control port is registered with the air exit, said aperture being at least large enough and said air outlet at least small enough to ensure that, when the device is used at 15 C. with a liquid having a penetrability by air flowing through the air outlet which is substantially less than the penetrability of a surface active detergent of viscosity 150 centistokes at 15 C., a portion of the aperture remains clear of the liquid being delivered, which portion is sufliciently large to permit air to How smoothly through the aperture counter-currently with the liquid, and the air outlet at a rate sufficient to replace the liquid but insufficiently large to permit such flow of air when the device is used at 15 C. with water.

3. A device for use with a liquid container having a liquid opening therein to seal said liquid opening and to enable liquid to be withdrawn from the container whilst simultaneously passing air thereto, which device comprises a gland adapted to engage the liquid open ing in fluid-tight relationship therewith, a sleeve-like extension on said gland positioned to project from the opening into the container, an air outlet and a liquid inlet formed through said extension on diametrically opposite sides thereof, a tubular body closed at both of its ends reciprocable through said gland in fluidtight relationship therewith, an aperture serving as an entrance for air to, and as an exit for liquid from, the tubular body formed in the wall of the body near the outer end thereof, an air control port formed in the wall of the tubular body on the opposite side from the said aperture, and a liquid control port formed through the wall of the tubular body on the same side as the said aperture, said liquid control port registering with the liquid inlet and said air control port registering with the air outlet when the tubular body is pulled outwardly through the gland to expose the whole of said aperture, said liquid control port being out of register with the liquid inlet and said air control port being out of register with the air outlet when the tubular body is pulled outwardly through the gland to expose a part of said aperture, and at least part of said air control port and at least part of said liquid control port projecting clear of the extension when the tubular body is pushed inwardly through said gland to cover the said aperture, said aperture being at least large enough and said air outlet at least small enough to ensure that, when the device is used at 15 C. with a liquid having a penetrability by air flowing through the air outlet which is substantially less than the penetrability of a surface active detergent of viscosity centistokes at 15 C., a portion of the aperture remains clear of the liquid being delivered, which portion is sufiiciently large to permit air to flow smoothly through the aperture counter-currently with the liquid, and the air outlet at a rate sufficient to replace the liquid but insufiiciently large to permit such flow of air when the device is used at 15 C. with water.

References Cited by the Examiner UNITED STATES PATENTS 482,408 9/92 Marsh 222-484 507,055 10/93 Wilson 222484 X 1,140,295 5/15 Tamagno 222-484 1,458,718 6/23 Lord 252-325 X 1,566,851 12/25 Frey 222-5l4 2,992,761 7/61 Sommers 222484 X FOREIGN PATENTS 320,145 10/29 Great Britain.

LOUIS J. DEMBO, Primary Examiner. 

1. A DEVICE FOR USE WITH A LIQUID CONTAINER HAVING A LIQUID OPENING THEREIN TO SEAL SAID LIQUID OPENING AND TO ENABLE LIQUID TO BE WITHDRAWN FROM THE CONTAINER WHILST SIMULTANEOUSLY PASSING AIR THERETO, WHICH DEVICE COMPRISES A GLAND ADAPTED TO ENGAGE THAT LIQUID OPENING IN FLUID-TIGHT RELATIONSHIP THEREWITH, A TUBULAR BODY RECIPROCABLE IN FLUID-TIGHT RELATIONSHIP THROUGH SAID GLAND, A SEAL CLOSINGL THE OUTER END OF SAID BODY, AN APERTURE SERVING AS AN AIR ENTRANCE AND AS A LIQUID EXIT FORMED IN THE WALL OF SAID BODY NEAR THE OUTER END THEREOF, SAID APERTURE BEING EXPOSED WHEN SAID BODY IS PULLED OUTWARDLY THROUGH SAID GLAND, AND CONCEALED WHEN SAID BODY IS PUSHED INWARDLY THROUGH SAID GLAND, A LIQUID INLET TO SAID BODY ON THE SAME SIDE THEREOF AS SAID APERTURE AND AN AIR OUTLET FROM SAID BODY ON THE OPPOSITE SIDE THEROF FROM SAID APERTURE, SAID LIQUID INLET AND SAID AIR OUTLET BEING POSITIONED TO COMMUNICATE WITH THE INTERIOR OF THE CONTAINER WHEN SAID BODY IS PULLED OUTWARDLY THROUGH SAID GLAND, SAID APERTURE BEING AT AT LEAST LARGE ENOUGH AND SAID AIR OUTLET AT LEAST SMALL ENOUGH TO ENSURE THAT, WHEN THE DEVICE IS USED AT 15* C. WITH A LIQUID HAVING A PENETRABILITY BY AIR FLOWING THROUGH THE AIR OUTLET WHICH IS SUBSTANTIALLY LESS THAN THE PENETRABILITY OF A SURFACE ACTIVE DETERGENT OF VISOCITY 150 CENTISTOKES AT 15*C., A PORTION OF THE APERTURE REMAINS CLEAR OF THE LIQUID BEING DELIVERED, WHCIH PORTION IS SUFFICIENTLY LARGE TO PERMIT AIR TO FLOW SMOOTHLY THROUGH THE APERTURE COUNTER-CURRENTLY WITH THE LIQUID AND THENCE THROUGH THE BODY, COUNTER-CURRENTLY WITH THE LIQUID, AND THE AIR OUTLET AT A RTE SUFFICIENT TO REPLACE THE LIQUID BUT INSUFFICIENTLY LARGE TO PERMIT SUCH FLOW OF AIR WHEN THE DEVICE IS USED AT 15*C. WITH WATER. 